The present invention relates to an absorbent article containing a superabsorbent polymer, which effectively prevents skin rash development without reducing the absorbing performance of the superabsorbent polymer. The present invention also relates to an absorbent article having an agent which has hardly been subjected to thermal history and by which scratches, rashes or inflammation of wearer"" skin can be suppressed or cured. The present invention also relates to fiber or a fiber aggregate having skin-care effects and suitable for use in these absorbent articles.
Absorbent articles developed for preventing rash development on wearer""s skin include those disclosed in WO96/16681 and WO96/16682. These publications show disposable diapers having a lotion containing an emollient applied to the topsheet. The lotion used contains an immobilizing agent for fixing the emollient to the topsheet.
Immobilized on the topsheet, the emollient hardly migrates to the wearer""s skin so that not all the emollient applied to the topsheet participates in antiinflammation. Some immobilizing agents used for fixing the emollient irritate the skin to produce a rash. The lotion sometimes gets hard to cause small scratches on the skin, which can also result in a rash.
In producing the above-described disposable diapers, the emollient is melted together with the immobilizing agent, and the molten mixture is applied to a topsheet. That is, the emollient is repeatedly exposed to high temperature for a long time (thermal history) and, as a result, often undergoes thermal denaturation or thermal decomposition. The immobilizing agent itself and the emollient in the presence of the immobilizing agent tend to become hard to scratch the skin. These agents are difficult to apply uniformly, which is a false economy.
Further, the disclosed disposable diapers are liable to leak because the immobilizing agent used is hydrophobic so that liquid waste discharged on the topsheet is not allowed to quickly permeate through the topsheet, rather tending to flow thereon. In order to secure smooth permeation of liquid, the amount of the lotion applied should be reduced, or application of the lotion must be discontinuous, but such manipulations will ruin the effects that should have been produced. In addition, the area in the topsheet where the lotion is applied interferes with smooth permeation of the liquid waste, resulting in remaining the liquid waste on the topsheet. The liquid waste remained on the topsheet causes swell of the wearer""s skin which leads to unfavorable skin rash due to, for example, scratch and infection of irritating substances.
There are some other known absorbent articles having a pharmacologically active ingredient to prevent a rash. However, without a proper choice of the active ingredient, the crosslinked structure of a superabsorbent polymer would be severed by the active ingredient to reduce liquid absorptivity and increase a back-flow. An increased back-flow brings skin overhydration, which accelerates a skin rash. A reduction in amount of the active ingredient only leads to a failure to exert the anti-rash effect.
Apart from the absorbent articles disclosed in the above publications, fibers having adhered thereto a skin-care agent have been proposed. Japanese Patent Laid-Open 5-44165 discloses chitosan-containing fiber, and Japanese Patent Laid-Open 8-60547 proposes sericin-containing fiber.
Chitosan and sericin generally have high crystallinity and low water solubility and are therefore not easy to apply in fiber processing. Specifically, chitosan or sericin precipitates and falls off while being adhered to fibers. As a result, the production equipment is soiled, and the resulting fiber has an insufficient add-on, and the adhesion is not uniform. A manipulation for increasing the add-on could result in more precipitation and fall-off, making a vicious circle.
Accordingly, an object of the present invention is to provide an absorbent article containing a superabsorbent polymer, which effectively prevents rash development without reducing the absorbing performance of the superabsorbent polymer.
Another object of the present invention is to provide an absorbent article having an agent fixed thereto with reduced involvement of thermal history so that the agent keeps effective in suppressing or curing scratches, a rash or inflammation of wearer"" skin.
Still another object of the invention is to provide an absorbent article which prevents discharged liquid waste from flowing on the skin-contacting surface thereof.
Yet another object of the invention is to provide an absorbent article containing an agent effective on the skin which exhibits improved stability while dry and manifests sufficient performance while worn.
A further object of the invention is to provide skin-care agent-containing fiber the skin-care agent of which has high water solubility to produce sufficiently high skin care effects.
A furthermore object of the invention is to provide skin-care agent-containing fiber having high skin care effects which can be produced by a simple process.
To accomplish the above objects, the present invention provides, in its first aspect, an absorbent article comprising a liquid retentive absorbent layer containing a superabsorbent polymer and a liquid-impermeable leak proof layer, wherein an agent having a skin care effect and substantially no decomposing action on the superabsorbent polymer is fixed on a prescribed region of the absorbent article in a state ready to be released from that region on contact with moisture.
The present invention also provides, in its second aspect, skin-care agent-containing fiber comprising fiber and an effective amount of a skin-care agent fixed on the fiber in a state ready to be released on contact with moisture.
The present invention also provides, in its third aspect, an absorbent article comprising a liquid retentive absorbent layer and a liquid-impermeable leak proof layer, wherein an agent having a prescribed effect on the skin of a wearer is fixed with a water-soluble thickener on a prescribed region of the absorbent article.